8. MORTGAGE LOANS AND NOTES PAYABLE

The Company’s mortgage loans and notes payable are summarized as follows:


	Carrying Value as of:
	December 31,		December 31,		Effective		Maturity
Mortgage Loans and Notes Payable	2017		2016		Interest Rate		Date
	(in thousands)
YSI 67	$	—	$	6,216	2.55	%	Mar-17
YSI 33		9,547		9,860	6.42	%	Jul-19
YSI 26		8,228		8,423	4.56	%	Nov-20
YSI 57		2,889		2,957	4.61	%	Nov-20
YSI 55		22,508		22,952	4.85	%	Jun-21
YSI 24		25,700		26,464	4.64	%	Jun-21
YSI 65		2,411		2,457	3.85	%	Jun-23
YSI 66		31,727		32,257	3.51	%	Jun-23
YSI 68		5,786		—	3.78	%	May-24
Principal balance outstanding		108,796		111,586
Plus: Unamortized fair value adjustment		3,286		3,742
Less: Loan procurement costs, net		(648)		(710)
Total mortgage loans and notes payable, net	$	111,434	$	114,618

As of December 31, 2017 and 2016, the Company’s mortgage loans payable were secured by certain of its self-storage properties with net book values of approximately $236.9 million and $233.1 million, respectively. The following table represents the future principal payment requirements on the outstanding mortgage loans and notes payable as of December 31, 2017 (in thousands):


2018	$	2,650
2019		11,652
2020		12,791
2021		45,057
2022		923
2023 and thereafter		35,723
Total mortgage payments		108,796
Plus: Unamortized fair value adjustment		3,286
Less: Loan procurement costs, net		(648)
Total mortgage loans and notes payable, net	$	111,434